Catalytic Activities of Electrochemically Dealloyed Pt(Pd)-Cu Catalysts for Oxygen Reduction Reaction

The electrochemically dealloyed Pt(Pd)-Cu catalysts were prepared by electrochemical dealloying of Cu3Pt(Pd) and their catalytic activities toward oxygen reduction reaction(ORR) were studied in 0.1 mol·L-1 HClO4 solution.The structural features of the dealloyed Pt(Pd)-Cu were revealed by synchrotron-based anomalous X-ray diffraction(AXRD) and surface X-ray scattering(SXS) at an atomic scale.We established a relationship between the structure and the catalytic activity by comparing the ORR activity and the structure of dealloyed Cu3Pt nanoparticles with similarly dealloyed Cu3Pt thin films and Cu3Pt(111).The enhancement in the activity of the dealloyed Pt(Pd)-Cu is mainly attributed to the strain change in the Pt(Pd) overlayer formed on the surface after dealloying.The strain is related to the thickness of Pt(Pd) overlayer,which is affected by the size of the material and the diffusion coefficient of the constituent element.The catalytic activity for ORR can be tuned by the strain in the surface layer of a catalyst.